If you get a core dump,
please send a backtrace if possible.
Before you try,
build mod_perl with perl Makefile.PL PERL_DEBUG=1 which will: -add `-g' to EXTRA_CFLAGS -turn on PERL_TRACE -set PERL_DESTRUCT_LEVEL=2 (additional checks during Perl cleanup) -link against libperld if it exists

If you get a segfault but no core file gets dumped and you cannot reproduce the segfault on will, you have to make sure that your environment is set to allow a core file to be dumped. Change the script that starts the server to do (in bash):

ulimit -c unlimited

before the code that starts the server. Alternatively you can execute this command from the shell and then start the server from the same shell. Now you should be able to get the core dumped.

Of course the directory the server is running in (usually as defined by ServerRoot) should be writable as well.